Elliptic curve ElGamal based homomorphic image encryption scheme for sharing secret images

This paper proposes an encryption scheme with a new additive homomorphism based on Elliptic Curve ElGamal (EC-ElGamal) for sharing secret images over unsecured channel. The proposed scheme enables shorter key and better performance than schemes based on RSA or ElGamal. It has a lower computation overhead in image decryption comparing with the method that uses other additively homomorphic property in EC-ElGamal. Elliptic curve parameters are selected to resist the Pohlig–Hellman, Pollard's-rho, and Isomorphism attacks. Experimental results and analysis show that the proposed method has superior performance to RSA and ElGamal. ► Exploit a new additive homomorphism in EC-ElGamal. ► Propose homomorphic image encryption for sharing secret images based on EC-ElGamal. ► Solve data expansion of EC-ElGamal. ► Uplift the encryption efficiency with shorter key length than methods based on RSA or ElGamal. ► Decrease the computation overhead in the decryption process.